1. Field of the Invention
The present invention relates to a movable clamping apparatus and more particularly to an apparatus which comprises a clamp provided on a slide and a bolster of a press machine or the like pedestal so as to be able to advance and retreat and locks the clamp at a retreated position.
2. Explanation of Related Art
A movable clamping apparatus of this type needs to be provided with a means for locking a clamp at a retreated position in order to prevent the clamp waiting at the retreated position from rattling due to vibration caused during a press working. Conventionally known as the locking means are a first prior art disclosed in Japanese Utility Model Public Disclosure No. 60-136826 and a second prior art recited in Japanese Patent Public Disclosure No. 10-231911.
The first prior art (UM Public Disclosure No. 60-136826) inserts a T-shaped leg of a clamp into a T-shaped groove of a slide of a press machine so that it can advance and retreat by a push-pull chain and pushes a dummy block provided laterally and outwardly of a starting end portion of the T-shaped groove through the clamp when having retreated the clamp to a waiting position.
According to the first prior art, the dummy block projects laterally and outwardly of the starting end portion of the T-shaped groove. Therefore, a movable clamping apparatus becomes large in shape and weight by an amount corresponding to the projection. This decreases a working space around the movable clamping apparatus to result in lowering the workability.
The second prior art (Patent Public Disclosure No. 10-231911) attaches a receiving block to a lateral and external side of a lower portion of a slide of a press machine and fits a T-shaped leg of a clamp into a T-shaped groove of the slide and a T-shaped groove of the receiving block movably. And it pushes the T-shaped leg of the clamp to the receiving block by pulling the clamp to a retreated position through a push-pull chain.
The second prior art need not be provided with the dummy block of the first prior art and therefore is excellent in that it can make the movable clamping apparatus compact and light by an amount corresponding to the omission of the dummy block. However, in order to attach the receiving block to the slide, the slide must be machined. Therefore, it takes labor to effect the machining. On this point, the second prior art has to be still improved.
The present invention has an object to provide a movable clamping apparatus which can increase a working space therearound and be easily attached.
In order to accomplish the object, the present invention has constructed a movable clamping apparatus in the following manner, for example, as shown in FIGS. 1 to 4 or in FIG. 5.
A clamp 5 has a housing 10 from which an engaging portion 11 projects. The engaging portion 11 is fitted into an engaging groove 2 of a pedestal 1, thereby enabling the clamp 5 to advance and retreat along the engaging groove 2. The clamp 5 is provided with a clamping piston 19 which moves relatively to the housing 10 and with a clamp member 6 to be driven by the piston 19. The clamp 5 is also provided with a locking means 8.
By switching over a push member 48 of the locking means 8 from a retracted position (N) to a projected position (M), the push member 48 at the projected position (M) pushes the pedestal 1, thereby fixing the engaging portion 11 to a peripheral wall of the engaging groove 2.
The present invention produces the following function and effect.
When placing the clamp in a waiting condition, it is sufficient if first, the clamp is moved to a retreated position by a fluid pressure cylinder and the like moving means or manually. Then the push member of the locking means pushes the pedestal and the thus resulting reaction force pushes the engaging portion to the engaging groove. This fixes the clamp to the pedestal through the engaging portion.
In this case, the clamp is provided with the locking means. Therefore, differently from the first prior art and the second prior art, it is possible to prevent the projection of the dummy block and the receiving block from the slide and the like pedestal.
This can increase the working space around the movable clamping apparatus to result in enhancing the workability.
Further, according to the present invention, the locking means is provided with or in the clamp. In consequence, differently from the second prior art, it is unnecessary to machine the slide and the like pedestal and besides to form an oil pressure passage, an air pressure passage and the like for driving the locking means in the pedestal. This facilitates the attachment of the movable clamping apparatus.
In addition, the present invention can further retreat the clamp by an amount corresponding to a space for installing the block required in each of the above-mentioned prior arts, which results in enlarging an allowance size for attaching a metal mold and the like object to be fixed.
The present invention includes various kinds of movable clamping apparatuses.
In one movable clamping apparatus, the locking means comprises a fluid pressure cylinder. When the clamping piston has moved for clamping with pressurized fluid, the pressurized fluid switches over the push member to the projected position. The apparatus can make a pressure supplying circuit for clamping of the clamp, common with a pressure supplying circuit for locking of the locking means. This results in the possibility of manufacturing whole the apparatus in compact size with a simple structure.
Further, as for the locking means, two cases are considered. In one case, it is attached to an outer surface of the housing of the clamp and in the other case, it is provided within the housing.
Moreover, it is preferable to provide a moving means for advancing and retreating the clamp and to connect an operation portion of the moving means to the housing. And it is also preferable if the moving means is constructed by a fluid pressure cylinder and the operation portion is composed of a piston rod.